Amyloidosis: Amyloidosis is a disease that results from the buildup of misfolded proteins known as amyloids. When proteins that are normally dissolvable in water fold to become amyloids, they become insoluble and deposit in organs or tissues.
Types of Amyloidosis
There are four main types of amyloidosis, each due to the deposition of a specific protein. The most common type is AL amyloidosis, caused by the deposition of light chain proteins produced by plasma cells in different disease states. The second most common is AA amyloidosis due to the accumulation of S amyloid A protein or SAA, which occurs in association with chronic infections – e.g. tuberculosis – or inflammatory illnesses such as rheumatoid arthritis.
The third and the fourth type are due to the deposition of a genetically defective or normal form of a protein called transthyretin respectively. Other minor forms of amyloid are also known.
Sign and Symptoms of Amyloidosis
The presentation of amyloidosis is broad and depends on the site of amyloid accumulation. The kidney and heart are the most common organs involved.
- Amyloid deposition in the kidneys can cause nephrotic syndrome.
- Amyloid deposition in the heart can cause both diastolic and systolic heart failure. EKG changes may be present, showing low voltage and conduction abnormalities like an atrioventricular block or sinus node dysfunction.
- Deposition of amyloids in the liver can lead to elevations in serum aminotransferases and alkaline phosphatase, two biomarkers of liver injury, which is seen in about one-third of people. Liver enlargement is common.
- Amyloid deposits in tissue and causes enlargement of structures. Twenty percent of people with AL amyloidosis have an enlarged tongue, that can lead to obstructive sleep apnea, difficulty swallowing, and altered taste. Tongue enlargement does not occur in ATTR or AA amyloidosis. Enlarged shoulders, “shoulder pad sign”, results from amyloid deposition in synovial space. Deposition of amyloid in the throat can cause hoarseness.
What causes AL amyloidosis
AL amyloidosis occurs when an abnormality in the plasma cells found in bone marrow results in the excessive production of proteins called ‘light chains’.
Usually, light chains form part of antibodies, but in cases of AL amyloidosis, large numbers of misfolded light chains are produced and this clump together into thread-like fibers that the body cannot clear away smoothly.
These fibers typically later gradually rise to form deposits in the heart, kidneys, nerves, or liver.
The abnormal white blood cells in the bone marrow are ordinarily benign (non-cancerous), but some cases of AL amyloidosis are linked to a type of bone marrow cancer called multiple myeloma.
Unlike some other types of amyloidosis, AL amyloidosis is not inherited, so a person with the condition cannot pass it on to their children.
Treating AL amyloidosis
There are currently no treatments available that can directly abstract the amyloid deposits associated with AL amyloidosis. Treatment aims to avert the further engendered of aberrant light chains while monitoring and treating any quandaries affecting your organs.
This can give your body enough time to gradually clear the deposits afore they build up again and can avail obviate organ damage.
In most cases, this will involve having chemotherapy to damage the anomalous bone marrow cells and inhibit engendered of the eccentric proteins.
You will additionally need treatment for organ failure – for example, you may need diuretic medication to treat heart failure and you may need dialysis if you have kidney failure.
Some people with kidney failure may be felicitous to receive a kidney transplant, albeit the underlying bone marrow disorder will require being suppressed by chemotherapy to avert the build-up of amyloid in the incipient kidney.
After chemotherapy, you will require conventional checkups every six to 12 months to probe for denotements of the condition returning (relapsing). If it does relapse at any stage, chemotherapy may need to be commenced again.
Afore efficacious treatments for AL amyloidosis were discovered, the perspective for the condition was poor, with many people only living for a few months.
With modern treatments, the perspective varies depending on the extent of the amyloid deposits, your age and general health, and how well you respond to treatment.
Overall, many people with AL amyloidosis now survive for several years after they are diagnosed with the condition and incrementing numbers of people are living for a decade or more.